DE102018132252B4 - Strain sensor, multi-axial force sensor and robot - Google Patents

Abstract

Strain sensor (1, 1a, 1b, 1c, 1d, 1e) comprising:
a linear bearing (5) with a first element (2) and a second element (3), which are mounted such that the first element (2) and the second element (3) only in one axial direction of a predetermined axis (A) are relatively mobile;
a connecting member (6, 6d, 6e, 16) having fixed portions (9a, 9ae, 9b, 9be, 19a, 19b) each attached to the first (2) member and the second member (3), and a strain generating portion (10, 10e) connecting the fixed sections together; and
a strain detection means (7, 17) which is arranged on the connecting element (6, 6d, 6e, 16) in order to be able to detect a strain in at least one direction of movement.

Description

{Technical area}

The present invention relates to a strain sensor, a multi-axial force sensor and a robot.

{General state of the art}

As a strain sensor that detects strain in the axial direction, a strain sensor is conventionally known, which is arranged between a nut movably arranged in the axial direction of a feed screw shaft and a movable table which is attached to the nut so as to detect a strain that is between Mother and the moving table acts (for example PTL 1). For a joint of a robot to which loads are applied in different axial directions in order to detect the loads in the axial directions applied to the joint with high accuracy, a strain compensation mechanism is formed from a bridge circuit using a large number of strain sensors capable of detecting strain in the axial direction, excluding loads in axial directions other than a particular axial direction along which detection is expected.

{Literature list}

{Patent literature}

{PTL 1} JP H05-138481 A

{Brief description of the invention}

{Technical problem}

However, a strain sensor is expensive, and therefore, using a large number of strain sensors for each propeller shaft leads to a problem that the cost of a robot increases.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a strain sensor, a multi-axial force sensor and a robot which can detect a load with high accuracy in a certain axial direction along which detection is expected while at the same time reducing costs by reducing the number of strain sensors.

{The solution of the problem}

In order to achieve the above-mentioned object, the present invention provides the following solutions.
According to one aspect of the present invention, there is provided a strain sensor comprising: a linear bearing having a first element and a second element supported such that the first element and the second element are relatively movable only in an axial direction of a predetermined axis A. are; a connecting member having fixed portions fixed to the first member and the second member, respectively, and a strain generating portion connecting the fixed portions to each other; and a strain detection means, which is arranged on the connecting element, in order to be able to detect a strain in at least one direction of movement.

According to this aspect, the first member and the second member are arranged so as to extend over a portion to which an axial force is transmitted, and the first member and the second member are fixed to an object to be detected, so that the axis coincides with an axis of the object to be detected which is moved along the predetermined axial direction. Accordingly, when a load is applied to the object to be detected, the first element and the second element move relative to each other, whereby a strain is generated at the strain generating portion of the connecting element. An amount of such strain is detected by the strain detection means, and thus a load in the axial direction of the linear bearing acting on the object to be detected can be detected based on the detected amount of strain.

In this case, the first element and the second element of the linear bearing are supported such that the first element and the second element are only movable in the axial direction relatively along that direction along which the first element and the second element are movable. Accordingly, even in the case where the strain sensor is attached to a joint of a robot on which loads act in different axial directions, it is possible to prevent loads in directions other than the moving direction of the linear bearing from acting on the strain generating portion of the connector . As a result, even without forming a strain compensation mechanism using a bridge circuit using a plurality of strain gauges, strains can occur in the axial direction along which the first element and the second element are movable, can be detected with high accuracy.

In the above-mentioned aspect, a cross-sectional area of the strain generating portion can be set smaller than a cross-sectional area of the fixed portion.

With such a configuration, the amount of strain at the strain generating portion is increased, and therefore the strain detecting means can detect a strain in the axial direction with high accuracy.

In the above-mentioned aspect, the first element and the second element may have fastening means for fastening the first element and the second element to an object to be detected.

With such a configuration, the first member and the second member can be directly attached to the object to be detected by the fastening means.

In the above-mentioned aspect, the connecting member may be formed to have a flat plate shape extending along a plane that is substantially parallel to the axial direction.

With such a configuration, the connecting member is arranged in a flat plate shape along the side surfaces of the first member and the second member, thereby reducing a protruding amount of the connecting member in the cross-sectional direction that is orthogonal to the axial direction.

In the above-mentioned aspect, the strain detecting means may include correcting means configured to correct a variation in the amount of strain caused by a change in the ambient temperature.

Even just changing the ambient temperature changes the amount of stretch. With the above configuration, however, the amount of elongation is corrected by an amount corresponding to the amount of change in the ambient temperature, and thus the accuracy in detecting the elongation can be further improved.

In the above-mentioned aspect, the strain detecting means may be fixed to the connecting member by screws.

In general, a strain gauge is attached by adhesion in many cases, so care must be taken to make an adhesive layer uniform. With the above configuration, however, the strain detecting means is fixed by screws, and thus assembly can be simplified.

In the above aspect, a plurality of strain detecting means may be arranged in a row on the strain generating section. With such a configuration, it is possible to know whether a strain detecting means is in a normal state by comparing strain data from one strain detecting means with strain data from another strain detecting means. Even if a failure occurs in the one strain detecting means, the robot can be quickly and safely stopped using strain information from the remaining normal strain detecting means which is not malfunctioning.

In the above-mentioned aspect, the linear bearing may be constituted by a linear ball bearing.

Even if the linear bearing is attached to a joint of a robot on which loads act in different axial directions, so that the first element and the second element are supported such that they are relatively movable only in the axial direction along which the first element and the second member are movable, it is possible to easily prevent a load in the axial direction along which the first member and the second member are movable from acting on the strain generating portion of the connecting member.

In the above-mentioned aspect, the linear bearing may be constituted by a linear roller bearing.

In the above-mentioned aspect, the linear bearing may be formed of a sliding bearing.

With such a configuration, a sliding bearing has a simple configuration, and thus costs can be reduced.

In the above-mentioned aspect, a plurality of connecting members may be provided at intervals in the moving direction, and the strain detecting means may be arranged at the strain generating portion of each of the connecting members.

With such a configuration, it is possible to easily form a strain sensor in which a plurality of identical connecting members are provided, each of which has a strain detection means so as to output detection values from a plurality of systems.

In the above-mentioned aspect, the strain sensor may include one or more reinforcement members configured to interconnect the first member and the second member, each of the reinforcement members being attached to the first member and the second member.

With such a configuration, the reinforcing member reduces the strain acting on the strain generating portion, and, compared with the case where the reinforcing member is not provided, the amount of strain that the strain detecting means detects is reduced. Accordingly, a detection value of the strain detecting means can be adjusted by the reinforcing member.

According to a further aspect of the present invention, there is provided a multi-axial force sensor comprising a plurality of the strain sensors described in any of the above configurations, wherein each of the axial directions of a plurality of the linear bearings is caused to coincide with each of a plurality of detection directions along which axial ones Forces are recorded.

According to this aspect, in the multi-axial force sensor, the strain sensors are arranged to cause the axial directions along which the strain sensors can detect strain to coincide with the plurality of detection directions along which the axial forces can be detected. Accordingly, the multi-axial force sensor can detect axial forces in the respective detection directions with high accuracy.

According to still another aspect of the present invention, there is provided a robot to which the strain sensor according to any of the above-mentioned configurations is mounted so as to cause the predetermined axis of the linear bearing to coincide with a linear movement axis of the robot having a linear movement shaft.

According to yet another aspect of the present invention, there is provided a robot comprising: an arm; and a multi-axial force sensor configured to detect axial forces in respective detection directions, the strain sensor being attached to at least a portion of the arm according to one of the above-mentioned configurations, causing the axial directions of the linear bearings of the strain sensors to coincide with a plurality of the detection directions of the Multiaxial force sensor coincide.

According to this aspect, it is possible to improve the accuracy in detecting the respective axial forces which the multi-axial force sensor mounted on the arm detects. Furthermore, a strain compensation mechanism using a plurality of strain gauges is not required, and thus the cost of the multi-axial force sensor can be reduced.

{Advantageous Effects of the Invention}

According to the present invention, it is possible to obtain an advantageous effect that a strain in the axial direction of a linear bearing can be detected with high accuracy while reducing the cost by reducing the number of the strain detecting means.

Figure list

• { 1 } 1 Figure 3 is a perspective view of a strain sensor according to an embodiment of the invention.
• { 2 } 2 Fig. 13 is a front view showing the strain sensor 1 represents.
• { 3 } 3 is a side view showing the strain sensor from 1 represents.
• { 4th } 4th Fig. 13 is a view showing an example in which the in 1 The strain sensor shown is mounted on a linear motion shaft of a linear motion arm of a robot.
• { 5 } 5 Fig. 3 is a cross-sectional view showing the Fig 1 shows the strain sensor attached to the linear motion arm of the robot.
• { 6th } 6th FIG. 13 is a side view showing a modification of the strain sensor of FIG 1 represents.
• { 7th } 7th FIG. 14 is a perspective view showing a modification of the strain sensor of FIG 1 represents.
• { 8th } 8th FIG. 14 is a perspective view showing a modification of the strain sensor of FIG 1 represents.
• { 9 } 9 FIG. 13 is a cross-sectional view showing a modification of the FIG 1 shown is the strain sensor attached to the linear motion arm of the robot.
• { 10 } 10 FIG. 14 is a perspective view showing a modification of the strain sensor of FIG 1 represents.

{Description of embodiments}

A strain sensor 1 and a robot 100 according to an embodiment of the present invention will be described below with reference to the drawings.

As in 1 to 3 shown, the strain sensor 1 according to this embodiment a linear roller bearing (linear bearing) 5 , a fastener 6th and a uniaxial strain sensor part (strain detecting means) 7th on. The linear roller bearing 5 has: a first element 2 and a second element 3 which are arranged side by side in the height direction; and a plurality of linear rollers 4 interposed between the first member 2 and the second element 3 are arranged at intervals in the direction of an axis A perpendicular to the height direction. The connecting element 6th is on the first element 2 and the second element 3 attached. The uniaxial strain sensor part 7th is attached to the connector 6.

As in 1 shown are multiple screw holes (fasteners) 8b in the second element 3 formed such that they extend along the height direction around the second element 3 to be attached to an object to be detected. Albeit in 1 not shown, substantially the same screw holes (fastening means) are also in a lower surface of the first member 2 educated.

As in 1 and 3 shown is the connecting element 6th formed in a flat plate shape to fit along end faces of the first member 2 and the second element 3 to be arranged substantially parallel to the direction of the axis A of the linear roller bearing 5 are. The connecting element 6th has fixed sections 9a , 9b on, each on side surfaces of the first element 2 and the second element 3 are attached, and a strain generating portion 10 who made the fixed sections 9a , 9b connects with each other.

The fixed section 9a is on the first element 2 attached, and the fixed section 9b is on the second element 3 attached. In the in 2 The example shown has the fixed section 9a a width dimension W1 and the fixed portion 9b has a width dimension W2 in the direction of axis A. The fixed section 9a and the fixed section 9b are arranged at different positions in the axial direction. The fixed section 9a that is on the first element 2 is attached, extends in the height direction upwards. The fixed section 9b that is on the second element 3 is attached, extends in the vertical direction downwards. The strain generating section 10 who made the fixed sections 9a , 9b connects with each other, has a width dimension W3 in the height direction, and is located at a position intermediate the fixed portions 9a , 9b in the direction of axis A near a boundary position between the first element 2 and the second element 3 is arranged. The strain generating section 10 connects the two fixed sections 9a , 9b together.

The cross-sectional area of the strain generating portion 10 is compared to the cross-sectional area of the solid sections 9a , 9b set sufficiently small. With such a setting, when a tensile force or a compressive force (hereinafter also simply referred to as "axial force") that causes the first element 2 and the second element 3 move in the direction of axis A relative to each other, between the first element 2 and the second element 3 acts as indicated by arrows in 2 is displayed only at the strain generating section 10 creates a stretch.

It causes the uniaxial strain sensor part 7th on a surface of the strain generating portion 10 adheres so that the detection direction of the uniaxial strain sensor part 7th coincides with the direction in which the axial force acts. A wiring not shown in the drawing is with the uniaxial strain sensor part 7th connected, and the uniaxial strain sensor part 7th outputs a voltage signal proportional to that at the strain generating section 10 amount of elongation generated. With such a configuration, there may be one at the strain generating portion 10 generated axial force can be detected based on the stress signal received from the uniaxial strain sensor part 7th is issued. For the uniaxial strain sensor part 7th For example, a semiconductor strain gauge, a metal foil strain gauge, or the like can be used. The sensor can be of the type that is fastened by bolts. Alternatively, the sensor may be composed of a displacement detecting device such as a laser displacement sensor, a laser proximity sensor, or a proximity sensor of an electrostatic capacitance type. Any sensor can be used provided the sensor can detect the amount of strain from a distance between the sensor and a counterpart. In this case, the projector side of the displacement detecting device and a wall-like member that is the counterpart must be on the same strain generating portion 10 be arranged.

The operation of the strain sensor 1 according to this embodiment having such a configuration will be described below.

In this embodiment, the case is described in which an axial force acting on a propeller shaft of the robot 100 acts using the strain sensor 1 is detected according to this embodiment.

As in 4th shown is the robot 100 a vertical articulated robot comprising: a rotating body 25th ; a first arm 26th ; a second arm 30th ; and a wrist unit 45 . The rotating body 25th is rotatable about a vertical first axis J1. The first arm 26th is in relation to the rotating body 25th rotatable about a horizontal second axis J2. The second arm 30th is at a distal end of the first arm 26th and is rotatable about a horizontal third axis J3. The wrist unit 45 is at a distal end of the second arm 30th arranged. The second arm 30th has an elongated base member 39 and a linear motion arm (object to be detected) 40 on. The base arm 39 is at the distal end of the second arm 30th arranged in a rotatable manner about the third axis J3. The linear motion arm 40 is in the longitudinal direction of the base element 39 movably mounted, and the wrist unit 45 is at a distal end of the linear motion arm 40 stored.

The linear motion arm 40 is by a linear movement mechanism in the longitudinal direction with respect to the base member 39 emotional. The linear movement mechanism has a linear guide 31, a slide 33 , a ball screw 32 and a motor 35. The linear guide 31 extends along the longitudinal direction (linear movement axis) B of the base member 39 . The slider 33 is movable along the linear guide 31. The ball screw 32 reaches into one on the slide 33 attached nut. The motor 35 causes the ball screw to move 32 rotates around a longitudinal axis.

As in 4th and 5 shown are the linear motion arm 40 and the slide 33 through a mounting plate 50 firmly fixed. At the same time is the strain sensor 1 according to this embodiment between the linear motion arm 40 and the slider 33 attached. The strain sensor 1 is fixed in such a way that the axis of the linear roller bearing 5 with the longitudinal direction B of the base element 39 coincides.

When the ball screw 32 by operating the motor 35, the slide is caused to rotate 33 at which the in the ball screw 32 engaging nut is fixed, moved along the linear guide 31 linearly. Such movement causes the linear motion arm to move 40 in the longitudinal direction with respect to the base element 39 of the second arm 30th emotional. When the linear motion arm 40 is made to move, a load acts on the linear motion arm 40 so that an axial force along the longitudinal direction B acts on the strain sensor 1 works. Due to such an axial force, the first element 2 and the second element 3 of the linear roller bearing 5 that has the strain sensor 1 forms, shifted slightly along the longitudinal direction B. Accordingly, due to such displacement, the axial force acts on the strain generating portion 10 that is between the fixed sections 9a , 9b of the connecting element 6th is arranged so that deformation of the strain generating portion 10 is effected. Due to such a deformation, the uniaxial strain sensor part detects 7th caused at the strain generation section 10 to adhere, the amount of elongation so that a tensile force or a compressive force can be detected based on the detected amount of elongation.

In this case, according to the strain sensor 1 this embodiment, the connecting element 6th , which is the strain generating section 10 having attached so that it is between the first element 2 and the second element 3 of the linear roller bearing 5 extends, and the first element 2 and the second element 3 are mounted in such a way that they only move in the direction of axis A relative to each other. Even with loads in different directions on the linear motion arm 40 of the robot 100 act, a tensile force or a compressive force acts only in the axial direction along the longitudinal direction B on the expansion generating section 10 on which the uniaxial strain sensor part 7th is appropriate.

That is, according to the strain sensor 1 In this embodiment, it is possible to achieve an advantageous effect that the strain sensor 1 even when loads in different directions on the linear motion arm 40 act, can only detect a tensile force and a compressive force acting along the longitudinal direction B with high accuracy.

Even without using a multiaxial strain compensation mechanism using a bridge circuit in which expensive strain sensors are attached for many directions, a tensile force and a compressive force along the axial direction can be detected with high accuracy without detecting the amount of elongation due to loads is generated in directions other than the axial direction. Accordingly, the cost can be reduced to a low level. Especially when strain sensors are on If all cardan shafts of an articulated robot are installed, costs can be effectively reduced.

In this embodiment, the sensor has been exemplified with the amount of strain at the strain generating section 10 from the uniaxial strain sensor part 7th is captured. However, a sensor that detects the amount of strain is not always limited to a uniaxial strain sensor. The sensor is not always limited to a uniaxial strain sensor, and a strain sensor can be used that detects the amount of strain at the strain generating portion 10 detected.

According to the strain sensor 1 of this embodiment is the uniaxial strain sensor part 7th on the connecting element 6th between the first element 2 and the second element 3 attached, and the connecting element 6th is formed in a flat plate shape along the side surfaces of the first member 2 and the second element 3 is arranged, which extend parallel to the axial direction. Accordingly, the connecting element 6th a compact configuration that is slightly in the cross-sectional direction orthogonal to the axial direction of the linear roller bearing 5 protrudes. With such a configuration, the strain sensor 1 on a cardan shaft of the robot 100 by using a gap in the vertical direction formed at a portion where the slider 33 and the linear motion arm 40 are attached.

According to the robot 100 where the strain sensor 1 This embodiment is attached to each articulated shaft, it is possible to achieve the beneficial effect that even when loads in multiple directions are applied to a distal end of the robot 100 act, an axial force that acts on each propeller shaft can be detected with high accuracy, whereby the robot 100 can be controlled. For example, a multi-axial force sensor that can detect axial forces in multiple axial directions can be one or more of multiple arms of the robot 100 be provided, and the strain sensors 1 the number of which corresponds to the number of corresponding axial directions can be used to detect one or two or more axial forces in the plural axial directions. In this case, the axial directions that the strain sensor 1 can detect coincide with the axial directions to be detected by the multiaxial force sensor.

In this embodiment, the linear roller bearing 5 used as a warehouse. However, the bearing is not based on the linear roller bearing 5 limited. If the bearing is mounted in such a way that the first element 2 and the second element 3 can only be moved in a predetermined direction of the axis A relative to each other, a bearing of another type, such as a linear ball bearing 5a , this in 6th is shown and has balls 4a, or a plain bearing can be used. In particular, is the amount of relative displacement between the first element 2 and the second element 3 for detecting an axial force is extremely small, and therefore a sliding bearing with a simple structure can be used. In such a case, a further cost reduction can be realized.

In this embodiment, the uniaxial strain sensor part 7th include correcting means configured to correct a variation in the amount of elongation caused by a change in the ambient temperature.

When an ambient temperature in the vicinity of the strain generating portion 10 of the connecting element 6th varies, the amount of stretching varies according to the amount of temperature change. With the above configuration, however, the amount of elongation is corrected using the correcting means by an amount corresponding to the amount of change in the ambient temperature, and thus the accuracy in detecting the elongation can be further improved.

In this embodiment, the uniaxial strain sensor part 7th exemplified the sensor made to be on the surface of the strain generating portion 10 to adhere. However, a sensor can be used, which is instead attached by screws.

Furthermore, the case was exemplified in which the strain sensor 1 the single uniaxial strain sensor part 7th having. However, two or more uniaxial strain sensor parts can be used 7th in a row on the strain generating section 10 be arranged to detect a malfunction. The uniaxial strain sensor parts 7th can be arranged in series or in parallel.

By applying the configuration in which the two or more uniaxial strain sensor parts 7th are arranged, it is possible to know whether there is a uniaxial strain sensor part 7th is in a normal state by reading strain data from the one uniaxial strain sensor part 7th with strain data from another uniaxial strain sensor part 7th be compared. Even if there is a malfunction in the one uniaxial strain sensor part 7th occurs, the robot can 100 quickly using strain information from the remaining normal uniaxial strain sensor part 7th safely stopped that is not malfunctioning.

7th shows a strain sensor 1b a modification, the two connecting elements 6th , 16 having. Compared to the strain sensor 1 of the embodiment as in 7th shown, the strain sensor 1b in addition to the connector 6th the connecting element 16 on which a uniaxial strain sensor part (strain detection means) 17th is attached. The connecting element 16 has the same configuration as the connector 6th , and the uniaxial strain sensor part 17th has the same configuration as the uniaxial strain sensor part 7th . The connecting element 16 is arranged so that the direction of the axis of the uniaxial strain sensor part 17th with the direction of the axis of the uniaxial strain sensor part 7th matches. Accordingly, the uniaxial strain sensor part 17th detect the amount of strain applied to the fastener 16 is produced.

As described above, the strain sensor 1b the in 7th modification shown the two connecting elements 6th , 16 and the two uniaxial strain sensor parts 7th , 17th along the direction of the same axis, thereby outputting detection values from multiple systems. In the in 7th An example has been described in which the strain sensor 1b the two connecting elements 6th , 16 and the two uniaxial strain sensor parts 7th , 17th having. A strain sensor of another embodiment, however, may have three or more connecting elements and three or more uniaxial strain sensor parts. Furthermore, the two connecting elements 6th , 16 have the same shape, and the two uniaxial strain sensor parts 7th , 17th can be identical to each other.

8th shows a strain sensor 1c a modification. The strain sensor 1c comprises two reinforcing elements 21, 22, each of which is on a first element 2 and a second element 3 attached to the first element 2 and the second element 3 to connect with each other. Two uniaxial strain sensor parts 7th , 17th are on a connector 6th arranged. Each of the reinforcement members 21, 22 is on the first member 2 and the second element 3 fastened by fastening bolts, and therefore the amount is attached to the connector 6th generated strain is less than the amount on the connecting element 6th generated strain on the strain sensor 1 the embodiment. Accordingly, detection values of the uniaxial strain sensor parts 7th , 17th attached to the connector 6th are arranged, through which reinforcement elements 21, 22 are adjusted. The two uniaxial strain sensor parts 7th , 17th can be identical.

In contrast to the in 8th shown strain sensor 1c For example, a strain sensor of another embodiment may have three or more uniaxial strain sensor parts attached to a connecting element 6th are arranged, or can have one or three or more reinforcing elements. In the 8th The reinforcement members 21, 22 shown have been described as an example of the reinforcement members that the strain sensor has. Provided, however, that the reinforcement element provided on the strain sensor has a shape that enables the reinforcement element to be attached to the first element 2 and the second element 3 To attach, the shape of the reinforcing element can be modified in various ways. For example, the reinforcing member can have the same shape as that in FIG 8th shown connecting element 6th , disc shape, or any other shape. The reinforcement elements can be on a side face of the strain sensor 1c be arranged on the side that is a side surface of the strain sensor 1c opposite on which the connecting element 6th is arranged.

The in 4th and 5 illustrated robot 100 are the slider 33 of the second arm 30th and the linear motion arm 40 through the mounting plate 50 attached to each other. As in 9 shown, the slide can 33 and the linear motion arm 40 but only through a strain sensor 1d be connected to each other. In this case the strain sensor receives 1d the total load of the linear motion arm 40 . Accordingly, the strain sensor 1d be designed so that the thickness of a connecting element 6d along the horizontal direction is larger than that of the strain sensor 1 who is in 4th and 5 is shown.

Regarding the strain sensor 1 of the above-mentioned embodiment, the connector 6th described where a cross-sectional area of the solid portion 9a , 9b is larger than a cross-sectional area of the strain generating portion 10 . The relationship between the cross-sectional areas of the respective sections of the connecting element 6th however, it can be modified in several ways. As in 10 shown, for example, has a connecting element 6e of a strain sensor 1e a modification has a rectangular shape when viewed in a front view. As an extreme example, a connecting element may have a flat plate shape covering the entire side surfaces of a first element 2 and a second element 3 covered. In contrast to the strain generating section 10 of the strain sensor 1 who is in 1 is shown, a strain generating portion 10e , where the uniaxial strain sensor 7th a strain detected, compared to other sections of the connecting element may not be formed with a small cross-sectional area. In another modification, a cross-sectional area of a strain generating portion of a connecting member may be set larger than a cross-sectional area of a fixed portion of the connecting member.

List of reference symbols

1, 1a, 1b, 1c, 1d, 1e

Strain sensor

2

first element

3

second element

5

Linear roller bearing (linear bearing)

5a

Linear ball bearings

6, 6d, 6e, 16

Connecting element

7, 17

uniaxial strain sensor part (strain detection means)

8b

Screw hole (fastener)

9a, 9ae, 9b, 9be, 19a, 19b

fixed section

10, 10e

Strain generating section

33

Slider (object to be recognized)

40

Linear motion arm (object to be detected)

100

robot

A.

Axis (predetermined axis)

B.

Longitudinal direction (linear movement axis)

Claims (15)

Strain sensor (1, 1a, 1b, 1c, 1d, 1e) comprising: a linear bearing (5) with a first element (2) and a second element (3), which are mounted such that the first element (2) and the second element (3) only in one axial direction of a predetermined axis (A) are relatively mobile; a connecting member (6, 6d, 6e, 16) having fixed portions (9a, 9ae, 9b, 9be, 19a, 19b) each attached to the first (2) member and the second member (3), and a strain generating portion (10, 10e) connecting the fixed sections together; and a strain detection means (7, 17) which is arranged on the connecting element (6, 6d, 6e, 16) in order to be able to detect a strain in at least one direction of movement. Strain sensor (1, 1a, 1b, 1c, 1d, 1e) Claim 1 wherein a cross-sectional area of the strain generating portion (10, 10e) is set smaller than a cross-sectional area of the fixed portion (9a, 9ae, 9b, 9be, 19a, 19b). Strain sensor (1, 1a, 1b, 1c, 1d, 1e) Claim 1 or 2 wherein the first element (2) and the second element (3) have fastening means (8b) for fastening the first element (2) and the second element (3) to an object (33, 40) to be detected. Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 3 wherein the connecting member (6, 6d, 6e, 16) is formed to have a flat plate shape extending along a plane that is substantially parallel to the axial direction. Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 4th wherein the strain detecting means (7, 17) includes correcting means configured to correct a variation in the amount of strain caused by a change in the ambient temperature. Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 5 , wherein the strain detection means (7, 17) is attached to the connecting element (6, 6d, 6e, 16) by screwing. Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 6th wherein a plurality of strain detecting means (7, 17) are arranged in a row on the strain generating section (10, 10e). Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 7th , wherein the linear bearing (5) is formed from a linear ball bearing (5a). Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 7th , wherein the linear bearing (5) is formed from a linear roller bearing. Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 7th , wherein the linear bearing (5) is formed from a plain bearing. Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 10 wherein a plurality of the connecting members (6, 6d, 6e, 16) are provided at intervals in the moving direction, and the strain detecting means (7, 17) is arranged on the strain generating portion (10, 10e) of each of the connecting members (6, 6d, 6e, 16). Strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 11 comprising one or more reinforcing members configured to interconnect the first member (2) and the second member (3), each of the reinforcing members being attached to the first member (2) and the second member (3) . Multiaxial force sensor, which comprises several strain sensors (1, 1a, 1b, 1c, 1d, 1e) which are in one of the Claims 1 to 12 are described, wherein each of the axial directions of a plurality of linear bearings (5) is formed such that it corresponds to each of a plurality of detection directions along which axial forces are detected. Robot (100) on which the strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to one of the Claims 1 to 12 is mounted such that the predetermined axis (A) of the linear bearing (5) coincides with a linear movement axis (B) of the robot (100) which comprises a linear movement shaft. A robot (100) comprising: an arm; and a multiaxial force sensor configured to detect axial forces in respective detection directions, the strain sensor (1, 1a, 1b, 1c, 1d, 1e) according to any of Claims 1 to 12 is attached to at least one portion of the arm, the axial directions of the linear bearings (5) of the strain sensors (1, 1a, 1b, 1c, 1d, 1e) coinciding with a plurality of detection directions of the multi-axial force sensor.

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